1. Field
The disclosed concept pertains generally to power distribution equipment and, more particularly, to electrical disconnect apparatus.
2. Background Information
Two primary objectives of the electric utility industry in the delivery of electrical power are safety and reliability.
Secondary network systems, for example, are used in certain locations such as downtown business districts and commercial areas in order to provide a high degree of service continuity. In such secondary network systems, a failure of any one distribution line will not result in an interruption of service to the customers since electrical power will be supplied to the customers over the remaining distribution lines. A network protector is employed in the event of a failure or fault to prevent power from the secondary network from being fed back through the network transformers to the fault. When a network protector is approached for, for example, maintenance, testing, or repair, the network protector must be electrically and physically disconnected from the power distribution equipment on both the network transformer side and the secondary network side. By way of example, arc flash, which is a dangerous condition associated with the explosive release of energy caused by an electrical arc due to either a phase-to-ground or phase-to-phase fault, is a serious safety concern.
FIGS. 1 and 2 show an example electrical disconnect apparatus 1, which includes a housing 100 and a connection device 200 having a handle 210. The housing 100 includes a first conductor 110 having a first conductive surface 111 configured to electrically connect to a first external circuit (not shown), and a second conductor 120 (FIG. 2) having a second conductive surface 121 (FIG. 2) configured to electrically connect to a second external circuit (not shown). As shown in FIG. 2, the first conductor 110 further includes a first receptacle 112 and a first flexible conductor 113, and the second conductor 120 further includes a second receptacle 122 and a second flexible conductor 123. The handle 210 is attached to a fuse 230, which includes opposing first and second conductive end portions 231,232 mechanically coupled by a tube 233 and electrically connected by a fusible element 234.
When the fuse 230 is inserted into the housing 100, it is received by the first receptacle 112 and the second receptacle 122 such that the first conductive end portion 231 contacts the first flexible conductor 113 and the second conductive end portion 232 contacts the second flexible conductor 123 to electrically connect the first and second conductors 110,120, which in turn creates a conductive circuit with the first and second flexible conductors 113,123 and the first and second conductive surfaces 111,121. Operating (e.g., turning and pulling) the handle 210 to partially remove the fuse 230 from the housing 100 moves the fuse 230 out of electrical contact with at least one of the flexible conductors 113,123, thereby electrically disconnecting the first conductor 110 from the second conductor 120. Thus, when the electrical disconnect apparatus 1 is employed, for example, between a network protector and an electrical network, a technician can relatively easily determine whether the network protector is isolated from the electrical network based on the presence or absence of the connection device 200 in the housing 100. The technician can also relatively easily electrically connect or disconnect the network protector from the electrical network by operating the handle 210 to insert or remove the connection device 200. However, this requires direct physical contact and manual operation of the connection device 200 on the part of the technician.
There is, therefore, room for improvement in electrical disconnect apparatus.